A flexible transmission, for example a belt transmission of an engine assembly presenting an endothermic engine and a plurality of accessories functionally connected to the endothermic engine by the flexible transmission, comprising generally a first turning pulley, at least one second pulley connected to an accessory and a belt wound around the pulleys to transfer the motion.
The first pulley is connected to a crankshaft of the engine and therefore the transmission is stressed by torsional vibrations whose harmful effects are generally attenuated by using dynamic dampers connected to the crankshaft and high yielding torsional joints interposed between the pulley and the crankshaft hub.
The torsional joints generally comprise a ring of elastomer material internally connected to the hub and outside the pulley, and presenting the disadvantage of deteriorating during the engine life and of having mechanical features considerably variable with temperature.